This invention relates to measuring fluorescence and properties derived from fluorescence in materials
Fluorescence refers to the property of some atoms and molecules to absorb light at a particular wavelength and to subsequently emit light of longer wavelength after a brief time interval, termed the fluorescence lifetime. Fluorescence illumination and observation is a rapidly expanding technique employed today, both in the medical and biological sciences. This has spurred the development of various kinds of sophisticated microscopes and other equipment that is suitable for analyzing fluorescence signals.
Fluorescent probes used in biological applications are typically constructed around synthetic aromatic organic chemicals designed to bind with a biological macromolecule. Fluorescent dyes are also useful in monitoring cellular integrity (e.g., live versus dead and apoptosis), endocytosis, exocytosis, membrane fluidity, protein trafficking, signal transduction, enzymatic activity, and so on. In addition, fluorescent probes have been widely applied to genetic mapping and chromosome analysis in the field of molecular genetics.
Some properties of fluorescent signals that have been used in biological applications include fluorescence intensity, fluorescence polarization/anisotropy, and fluorescence lifetime. Fluorescence intensity can be used to provide an indication of the presence (and possibly also the amount) of a particular fluorophore in a sample. Fluorescence anisotropy can provide a measure of the degree to which fluorescent radiation is non-randomly polarized, that is, the degree to which one polarization orientation predominates over its orthogonal polarization orientation. A highly anisotropic signal is highly polarized (for example, linearly polarized). A highly isotropic signal approaches random polarization. In one conventional approach, anisotropy (r) is calculated using the following equation:
  r  =            VV      -      gVH              VV      +              2        ⁢        gVH            where VH and VV are the horizontal and vertical polarizations (relative to vertically polarized excitation light) and g corrects for polarization bias of the optical instrument used to detect the fluorescence. Fluorescence lifetime can be used, for example, to classify the microenvironment of a particular analyte in a sample.
Many of today's fluorescence analysis systems work well in laboratory settings. However, in the chemical and biotechnology industry, there is often a need to analyze a large number of samples in a time and cost-efficient manner. Due to the different requirements in these environments, many fluorescence analysis systems are not suitable or possible to use and, as a result, the range of analyses that can be performed in an industrial setting is more limited than that of a laboratory setting.